The invention concerns devices for operating blinds placed inside a glass-enclosed chamber.
It is a well-known fact that much heat is lost from within residential buildings through the glass panes of windows and french windows but that such dispersion can be greatly reduced by fitting double glazing with a hermetically sealed chamber between the panes.
The presence of a blind, including the venetian or pleated types, inside the glass-enclosed chamber leads to complications because of the need to work it from outside without interfering with the hermetic seal.
Various operating systems have been devised and applied connecting interrnal and external kinematic mechanisms by lines of magnetic forces acting through one of the panes.
Such devices are however substantially complex and costly.
The chief complications concern the need to ensure that, when moving, the various parts of the blind remain parallel one to another. Use of an internal electric motor greatly increases costs because of the need for reduction mechanisms.
Purely mechanical controls from outside, such as cords, create problems due to the tendency to slippage between internal and external mechanisms connected by magnetic forces.